The day 14 thing doesnt fit every woman. Every woman is different on their fertile time. To be honest,unless you are charting and completely understand your body,there isnt a safe time to have sex without worrying over pregnancy. Even knowing your body and charting doesnt give you free rein on avoiding pregnancy.
Go to either the pregnancy or teen sex board and read the sticky titled Pregnancy info for Teens,etc(that one is on the pregnancy board),the teen board one is titled Contraception/pregnanacy info for teens. It has a lot of info on it.

regardless of weather you are fertile or not, sperm, surprisingly can live in your uterus/fallopian tubes for up to two whole weeks! you should go on the pill or another contraceptive if you want to have untprotected sex

Sperm can not survive two weeks inside the uterus...it just cant simply because the uterus doesnt stay in the fertile stage that long. The fertile stage is key for the sperm being able to survive. Granted there have been some studies that found some men have sperm that can survive up to 10 days inside a woman but generally the time frame is between 3 to 7 days not 2 weeks.

A good book to read is Taking Charge Of Your Fertility by Toni Weschler. She wrote a wonderful book that is easy to read and very helpful in understanding the female body and the way cycles actually work.

After just finishing getting my period, is this the safe time that I am not fertile until the 14 day of ovulating? Is there a chance of being fertile the day after I finish getting my period?

As Blastoff said, every woman does not ovulate on day 14 of her cycle, especially since women's cycles can vary in length. I have almost always been extremely regular (28 or 29 day cycles) and I know precisely which day I ovulate (discharge plus slight pain in one ovary) and I can tell you ovulation is not always day 14. It usually is very close to that, but not precisely. And once in a while I'll have a longer or shorter period. If you were simply assuming day 14 = ovulation, and it's a "whacky" cycle, you've made a big mistake.

Anyway, if you know defintely what day you ovulate, then wait a day or two beyond that, then you enter your "safe" time. The egg is only viable for 24 hours, so once that time has passed, you cannot get pregnant. If you get PMS symptoms, you can also wait until they appear to have unprotected sex. Do I recommend this for most people? NO. You'd have to know your body extremely well and accept the pregnancy risk if you miscalculate.

As for there being a chance of ovulating the day after you finished your period, I'd say that that is something that *could* happen, although probably unlikely. Also, the uterus would not be physically ready to accept a fertilized egg should conception occur anyway. But just remember (as pointed out above) if you have unprotected sex the day after your period ends, the sperm could live in your reproductive tract for 5 days and you could very well ovulate 5 days later, and get pregnant.

The bottom line is, if you don't wish to get pregnant, assume no days are "safe" and use adequate protection

Sperm can not survive two weeks inside the uterus...it just cant simply because the uterus doesnt stay in the fertile stage that long. The fertile stage is key for the sperm being able to survive. Granted there have been some studies that found some men have sperm that can survive up to 10 days inside a woman but generally the time frame is between 3 to 7 days not 2 weeks.

A good book to read is Taking Charge Of Your Fertility by Toni Weschler. She wrote a wonderful book that is easy to read and very helpful in understanding the female body and the way cycles actually work.